Dynamic supplemental downforce control system for planter row units

ABSTRACT

A dynamic supplemental downforce control system for a planter row unit. The system includes closed-loop feedback circuit that cooperates with a downforce actuator to dynamically control fluid flow to the downforce actuator to maintain balance between the actual gauge wheel downforce and a desired gauge wheel downforce during planting operations.

BACKGROUND

It is recognized that sufficient downforce must be exerted on a planterrow unit to ensure the desired furrow depth and soil compaction isachieved. If excessive downforce is applied, especially in soft or moistsoils, the soil may be overly compacted which can affect the ability ofgerminating seeds to break through the soil. If insufficient downforceis applied, particularly in hard or dry soil, the planter may ride upand out of the soil resulting in insufficient depth of the furrow.

In the past, coiled springs extending between the parallel arms of therow units of the planter (see FIG. 1) were often employed to provide theadditional or “supplemental” downforce needed to ensure the desiredfurrow depth and soil compaction was achieved. By positioning the springat various preset locations along the parallel arms, the amount ofdownforce exerted on the row unit could be increased or decreased.However, the amount of supplemental downforce exerted by the springremained constant until the spring was repositioned. For example, whenthe planter encountered hard or dry soil such that greater supplementaldownforce is necessary to maintain furrow depth or the desired soilcompaction, the operator had to stop and adjust the location of thespring in order to increase the supplemental downforce. Furthermore,during operation, as the seed or fertilizer in the hoppers wasdispensed, the weight of the row unit gradually decreased causing acorresponding reduction in the total downforce on the gauge wheels,because the supplemental downforce exerted by the spring remainedsubstantially constant until the spring was manually repositioned.

More advanced supplemental downforce systems, such as disclosed in U.S.application Ser. No. 12/679,710 (Pub. No. US2010/0198529) by Sauder etal. (hereinafter “the Sauder '710 Application”), which is incorporatedherein in its entirety by reference, measure the strain in a member ofthe gauge wheel adjusting mechanism to determine the force being exertedagainst the gauge wheels to determine the downforce. A central processoror controller actuates the hydraulic or pneumatic cylinders, airbags orother actuators to increase or decrease the supplemental downforceacross all the row units. While such systems may serve their intendedpurpose, they can be more costly because they require central processingcircuitry as well as hydraulic or pneumatic valves, load sensors, andassociated cable harnesses at each row unit in order to properlymaintain the desired downforce. Moreover, the required processing stepsincrease the response time of such a system as compared with the use ofcoil springs or other earlier mechanical systems for supplyingsupplemental downforce. In addition, central control systems that applya common supplemental downforce to each row unit fail to respond tounique loads experienced by each row unit, such that insufficient orexcessive supplemental downforce may be applied to any given row unit.

Thus, there is a need for a supplemental downforce control system thatmaintains a desired downforce at each row unit and additionally allowsan operator to set the desired downforce from the tractor cab whileon-the-go during planting operations.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation view of a conventional planter row unitshowing the use of a prior art coil spring to provide supplementaldownforce.

FIG. 2 is a schematic view of another conventional planter row unitshowing the use of a prior art coil spring to provide supplementaldownforce.

FIG. 3 is a side elevation view of the conventional planter row unit ofFIG. 1 with an embodiment of a dynamic supplemental downforce controlsystem.

FIG. 4 is a side elevation view of the conventional planter row unit ofFIG. 2 with another embodiment of a dynamic supplemental downforcecontrol system.

FIG. 5 is a schematic illustration of an embodiment of closed-loopfeedback circuit for the dynamic supplemental downforce control systemof FIGS. 3 and 4.

FIG. 6 is a schematic view of an embodiment of the direction controlvalve for the supplemental downforce control systems of FIGS. 3 and 4.

FIGS. 7A-7C illustrate fluid flow and operation of the direction controlvalve and downforce actuator of FIGS. 3 and 4 utilizing fluid pressurefrom a pilot pressure control valve to impart the desired gauge wheeldownforce Fd.

FIGS. 8A-8C illustrate fluid flow and operation of the direction controlvalve and downforce actuator of FIGS. 3 and 4 utilizing a solenoid toimpart the desired gauge wheel downforce Fd.

FIG. 9 is a schematic illustration of a portion of another embodiment ofthe closed-loop feedback circuit of FIG. 5 but with the pilot pressurecontrol valve replaced with a manually operated pressure regulatingvalve.

FIG. 10 is a partial side elevation view of another embodiment of thedynamic supplemental downforce control system of FIG. 4 illustrating apiezoelectric load cell.

DESCRIPTION

Referring now to the drawings, wherein like reference numerals designateidentical or corresponding parts throughout the several views, FIG. 1illustrates a side elevation view of a single row unit 10 of aconventional row crop planter such as the type disclosed in U.S. Pat.No. 4,009,668, incorporated herein in its entirety by reference. As iswell known in the art, the row units 10 are mounted in spaced relationalong the length of a transverse toolbar 12 by a parallel linkage 14,comprised of upper and lower parallel arms 16, 18 pivotally mounted at aforward end to the transverse toolbar 12 and at their rearward end tothe row unit frame 20. The parallel linkage 14 permits each row unit 10to move vertically independently of the toolbar 12 and independently ofthe other spaced row units in order to accommodate changes in terrain orupon the row unit encountering a rock or other obstruction as theplanter is drawn through the field.

The row unit frame 20 operably supports a seed hopper 22, and a smallerhopper 24 for insecticide and/or fertilizer, a seed meter 26 and a seedtube 28 as well as a furrow opener assembly 30 and furrow closingassembly 40. The furrow opening assembly 30 comprises a pair of furrowopener discs 32 and a pair of gauge wheels 34. The gauge wheels 34 arepivotally secured to the row unit frame 20 by gauge wheel arms 36. Afurrow depth adjusting member 38 adjustably positions the gauge wheels34 relative to the furrow opener discs 32 for establishing the desiredfurrow depth. A coil spring 50 is disposed between the parallel arms 16,18 to provide supplemental downforce to ensure that the furrow openerdiscs 32 fully penetrate the soil to the desired depth as set by thedepth adjusting member 38 and to provide soil compaction for properfurrow formation. Rather than a coil spring, supplemental downforce maybe provided by actuators or other suitable means such as disclosed inU.S. Pat. No. 6,389,999 to Duello, U.S. Pat. No. 6,701,857 to Jensen, inEuropean Patent No. EP0372901 to Baker, and/or the Sauder '710Application.

In operation, as the row unit 10 is lowered to the planting position,the opener discs 32 penetrate into the soil. At the same time, the soilforces the gauge wheels 34 to pivot upwardly until the gauge wheel arms36 abut or come into contact with the stop position previously set withfurrow depth adjusting member 38 or until a static load balance isachieved between the vertical load of the row unit and the reaction ofthe soil. As the planter is drawn forwardly in the direction indicatedby arrow 39, the furrow opener discs cut a V-shaped furrow 60 into thesoil while the gauge wheels 34 compact the soil to aid in formation ofthe V-shaped furrow. Individual seeds 62 from the seed hopper 22 aredispensed by the seed meter 26 into the seed tube 28 in uniformly spacedincrements. The seed tube 28 directs the individual dispensed seeds 62downwardly and rearwardly between the furrow opener discs 32 and intothe bottom of the V-shaped furrow 60. The furrow 60 is then covered withsoil and lightly compacted by the furrow closing assembly 40.

FIG. 2 illustrates a side view of another embodiment of a conventionalrow unit 10 for a central-fill planter such as disclosed in U.S. Pat.No. 7,438,006, incorporated herein in its entirety by reference. As inthe row unit embodiment of FIG. 1, the row unit embodiment of FIG. 2includes a parallel arm linkage 14 comprised of upper and lower parallelarms 16, 18 pivotally mounted at a forward end to the transverse toolbar12 and at their rearward end to the row unit frame 20. The row unitframe 20 supports a mini seed hopper 23, seed meter 26, a seed tube 28,as well as the furrow opener assembly 30, comprising a furrow openerdiscs 32 and gauge wheels 34. The gauge wheels 34 are pivotally securedto the row unit frame 20 by gauge wheel arms 36. Unlike the embodimentof FIG. 1, the gauge wheel arms 36 in the embodiment of FIG. 2 extendforwardly of the gauge wheels 34.

The row units 10 in FIGS. 3 and 4 are substantially the same as the rowunits 10 depicted in FIGS. 1 and 2, respectively, except that in FIGS. 3and 4, the coil springs 50 have been removed and replaced with anembodiment of a dynamic supplemental downforce control system 100 inaccordance with the present invention.

FIG. 5 schematically illustrates a preferred embodiment of the automatedsupplemental downforce control system 100 which comprises a closed-loopfeedback circuit 110 that cooperates with a downforce actuator 200.Preferably, the dynamic system 100 utilizes the hydraulic system of thetractor pulling the planter and therefore preferably comprises anelectro-hydraulic closed-loop feedback circuit 110 and a dual actionhydraulic cylinder 200. However, the dynamic system 100 may be equallyadapted for use with pneumatic actuators in cooperation with anycorresponding electro-pneumatic closed-loop feedback circuit. It shouldalso be appreciated that although the schematic illustration of FIG. 5shows the dynamic system 100 in relation to a four-row planters, thedynamic system 100 can be adapted to a planter with any number of rowunits.

As used herein, the term “actual gauge wheel downforce” Fa (FIGS. 3 and4) refers to the dead load, live load and supplemental downforcetransferred to the soil through the gauge wheels 34 of the row unit 10.The row unit dead load is understood to be the mass of the entire rowunit and any accessories mounted thereon. Therefore, the row unit deadload remains substantially constant and would include the mass of therow unit frame 20, the furrow opening assembly 30, the furrow closingassembly 40, the hoppers 22, 24, seed meter 26, seed tube 28 and themass of any other attachments or devices operably supported or carriedby the row unit frame. The row unit live load is understood to be themass of the seed, insecticide and/or fertilizer within the hoppers 22,24, 23 of the row unit or otherwise carried by the row unit. The liveload typically varies as the material is dispensed during plantingoperations.

The term “supplemental downforce,” as used herein refers to the loading,other than the live load and dead load, that is applied to the row unitto force the row unit downwardly or upwardly relative to the toolbar 12to achieve the desired furrow depth and soil compaction under the gaugewheels 34. It should be understood that the supplemental downforce mayincrease or decrease the actual gauge wheel downforce Fa. It isrecognized that a certain amount of the row unit dead load, live loadand supplemental downforce is carried by the furrow opener discs 32 andthe furrow closing assembly 40. Nevertheless, because the preferredsystem and method 100 disclosed herein preferably involves only theforces or loads exerted on or transferred by the gauge wheels, thenloads transferred by the opener discs and closing wheel need not beconsidered.

Referring to FIGS. 3 and 4, it should be appreciated that if thedownforce actuator 200 is extended, the row unit 10 will be forceddownwardly relative to toolbar 12, resulting in an increase in thesupplemental downforce and a corresponding increase in the actual gaugewheel downforce Fa. Likewise, if the downforce actuator 200 isretracted, the row unit 10 will be pulled upwardly relative to thetoolbar 18, resulting in a decrease in the supplemental downforce and acorresponding reduction in the actual gauge wheel downforce Fa.

Referring to FIG. 5, the preferred electro-hydraulic closed-loopfeedback circuit 110 comprises a control module 112, a pilot pressurecontrol valve 114, one load sensor 116 (preferably one per row unit), atleast one direction control valve 140 (preferably one per row unit),fluid lines 122 and signal lines 124. As described in greater detaillater, a lever 136 (FIGS. 3 and 4) is preferably disposed to transmitthe up and down directional displacement of the gauge wheels and thusthe corresponding actual gauge wheel downforce Fa, to the directioncontrol valve 140. The signal lines 124 communicate electrical signalsbetween the control module 112, the load sensor 116, the pilot pressurevalve 114, and the direction control valve 140. The fluid linescommunicate hydraulic fluid between a fluid source 130, the pilotpressure control valve 114, the direction control valve 140 and thedownforce actuator 200. The fluid source 130 is preferably the hydraulicfluid reservoir of the tractor pulling the planter. It should beappreciated that if the dynamic system 100 is an electro-pneumaticsystem, the fluid source may be an air compressor, compressed air tankor other suitable air source.

In general, through the control module 112, the operator is able to setthe desired gauge wheel downforce Fd, which, in one embodiment,corresponds to the output pressure of the pilot pressure control valve114. The control module 112 also preferably permits the operator to viewthe actual gauge wheel downforce Fa of the row units 10 as detected bythe load sensors 116. The direction control valve 140 permits fluid flowto and from the individual downforce actuators 200 in response to anyimbalance between the desired gauge wheel downforce Fd acting at one endof the direction control valves 140 against the actual gauge wheeldownforce Fa acting at the other end of the direction control valves140. Thus, the dynamic system 100 independently and dynamically adjuststhe supplemental downforce for each individual row unit as each row unitexperiences unique loading conditions during planting operations. Thedownforce adjustment occurs without the need for complex and expensivecentral processing circuitry or software programming that wouldotherwise be required to simultaneously monitor and compare the desiredgauge wheel downforce Fd with the actual gauge wheel downforce Fa acrossall row units and to then send signals to independently control thedownforce actuators 200 at each row unit.

Although it is preferable for each row unit 10 to have separate loadsensor 116 so the operator can monitor the actual gauge wheel downforcefor each row, it may be desirable to have load sensors on only certainrow units, such as on the outside row units and one or two inner rowunits. It should also be appreciated that although it is desirable foreach row unit 10 to have a direction control valve 140, a singledirection control valve 140 may be used to control fluid flow to thedownforce actuators 200 of multiple row units. Similarly a singledownforce actuator 200 may be utilized to control the supplementaldownforce across multiple row units.

The pilot pressure control valve 114 is in fluid communication with thefluid source 130 via fluid lines 122 a and the direction control valve140 via fluid lines 122 b. It is also in electrical communication withthe control module 112 via signal lines 124 a. The operator is able toset the desired output pressure of the pilot pressure control valve 114via the control module 112. Suitable pilot pressure control valvesinclude solenoid-operated proportional valves such as model no. PV72-21distributed by HydraForce, Inc. in Lincolnshire, Illinois.

The load sensor 116 is disposed to preferably generate an electricalsignal corresponding to the actual gauge wheel downforce Fa (FIGS. 3-5).The control module 112 receives the generated signal from the loadsensor 116 via the signal lines 124 b and preferably displays to theoperator the actual gauge wheel downforce Fa corresponding to thegenerated signal. In a preferred embodiment, the load sensor 116 is astrain gauge such as a Wheatstone bridge circuit mounted in any suitablelocation from which the actual gauge wheel downforce Fa can bereasonably accurately determined. For example, the load sensor 116 maybe mounted to detect the strain in the gauge wheel arm 36 (FIGS. 4 and5) such as disclosed in U.S. Pat. No. 6,389,999 to Duello, or US PatentNo. 6,701,857 to Jensen, or the strain in the pivot pin of the depthadjusting member 38 (FIG. 3), such as disclosed in the Sauder '253Application, or in the equalizer for the depth adjusting member asdisclosed in U.S. Provisional Application No. 60/883,957 filed Jan. 8,2008 by Sauder et al., or in a location such as disclosed in EuropeanPatent No. EP0372901 to Baker. All of the above-referenced patentsand/or patent applications are incorporated herein in their entiretiesby reference.

The control module 112 is preferably integrated into an existing plantermonitor that provides a user interface, such as a touch screen, keypador other input means, through which the operator can select or input thedesired gauge wheel downforce Fd. The control module 112 is alsopreferably integrated into an existing planter monitor that provides adisplay screen or other visual display through which the operator canview and monitor the actual gauge wheel downforce Fa of the row units.In a preferred embodiment, the control module 112 is integrated into the20/20® planter monitor system sold by Precision Planting, Inc., ofTremont, Ill. and as disclosed in U.S. patent application Ser. No.12/522,252 (Pub. No. US2010/0010667) by Sauder et al., incorporatedherein in its entirety by reference. Those skilled in the art wouldreadily understand how to modify the 20/20® planter monitor or any otherplanter monitor to integrate the additional programming and circuitrynecessary to allow an operator to input a desired gauge wheel downforceFd for controlling the output of the pilot pressure valve 114 and toalso receive and display the actual gauge wheel downforce Fa as detectedby the load sensor 116. Alternatively, as would be recognized by thoseskilled in the art, the control module 112 may be a standalone systemincorporating the necessary circuitry for controlling the outputpressure of the pilot control valve 114 corresponding to the desiredgauge wheel downforce Fd, and/or for displaying the actual gauge wheeldownforce Fa of the row units. Regardless of whether the control module112 is integrated into an existing planter monitor system or as astandalone unit, it is preferably mounted in the cab of the tractor in alocation where an operator can view and interact with the user interfaceduring planting operations.

Referring to FIGS. 6 and 7A-7C, the direction control valve 140 ispreferably a three-position directional control valve similar such asmodel no. PTS16-12 distributed by Eaton Corporation, Eden Prairie, Minn.The direction control valve 140 preferably includes a housing 142 havingan axial through-bore 144 and an enlarged counterbore 146. A series ofports extend transversely through the sidewall 148 of the housing 142and into the axial through-bore 144, preferably including an inlet port150, first and second fluid return ports 152, 154, and first and secondactuator ports 156, 158. A spool 160 is slidably disposed within thehousing 142. The spool 160 has a shaft 162 and an enlarged head 164. Theenlarged head 164 is disposed within the counterbore 146. A spring 166biases the spool head 164 leftward as viewed in FIG. 6. The shaft 162includes two longitudinally spaced circumferential rings 168. Thecircumferential rings 168 define raised surfaces, which, when alignedwith the first and second actuator ports 156, 158 as shown in FIG. 6effectively block the flow of fluid into or out of the ports and preventpassage of fluid from one side of the circumferential ring to the other.Thus, as illustrated in FIGS. 7A-7C, the movement of the spool 160within the through-bore 144 functions as a three position valve. Thedirection control valve 140 further includes a head cap 170 and an endcap 172. The head cap 170 includes an axial end port 174 in fluidcommunication with an axial counterbore 176. A block 178 is slidablydisposed within the axial counterbore 176 and abuts the spring biasedspool head 164. The end cap 172 has an axial bore 180 through which thedistal end of the spool shaft 162 extends. O-rings 182 are provided tofluidly seal the head cap 170 and end cap 172 with the housing 142.

In operation, referring to FIGS. 5, 6 and 7A-7C, fluid lines 122 bcommunicate fluid from the pilot pressure valve 114 to the axial endport 174 of the direction control valves 140 at a pressure correspondingto the desired gauge wheel downforce Fd. Another set of fluid lines 122c communicate pressurized fluid from the fluid pressure source 130 tothe inlet port 150 of each direction control valve 140. Another set offluid lines 122 d communicate fluid between the fluid return ports 152,154 back to the fluid source 130. Another set of fluid lines 122 ecommunicate fluid between the first and second actuator ports 156, 158to each side of the piston 202 within the downforce actuator 200 of eachrow unit 10. The lever 136 (FIGS. 3 and 4) transmits the opposing actualgauge wheel downforce Fa to the distal end of the spool shaft 162 of thedirection control valve 140.

As depicted in FIG. 7A, if the desired gauge wheel downforce Fd is thesame as the actual gauge wheel downforce Fa transmitted by the lever 136(i.e., Fd=Fa), the circumferential rings 168 on the spool shaft 162 arepreferably aligned with the first and second actuator ports 156, 158thereby preventing fluid flow to and from the downforce actuator 200.

As depicted in FIG. 7B, if the desired gauge wheel downforce Fd isgreater than the actual gauge wheel downforce Fa transmitted by thelever 136 (i.e., Fd>Fa), the spool shaft 162 will be forced to the rightopening fluid communication between the fluid inlet port 150 and thesecond actuator port 158 and opening fluid communication between thefirst actuator port 156 and the first fluid return port 152 therebyallowing fluid to flow into the piston end of the downforce actuator 200and out through the rod end of the downforce actuator 200 forcing thepiston 202 downwardly thereby increasing the actual gauge wheeldownforce Fa. When the actual gauge wheel downforce Fa is sufficientlyincreased to rebalance with the desired gauge wheel downforce Fd, thespool shaft 162 will return to the position as show in FIG. 7A.

As depicted in FIG. 7C, if the desired gauge wheel downforce Fd is lessthan the actual gauge wheel downforce Fa transmitted by the lever 136(i.e., Fd<Fa), the spool shaft 162 will be forced to the left openingfluid communication between the fluid inlet port 150 and the firstactuator port 156 and opening fluid communication between the secondactuator port 158 and the second fluid return port 154 thereby allowingfluid to flow into the rod end of the downforce actuator 200 and outthrough the piston end of the downforce actuator 200 forcing the piston202 upwardly thereby decreasing the actual gauge wheel downforce Fa.When the actual gauge wheel downforce Fa is sufficiently decreased torebalance with the desired gauge wheel downforce Fd, the spool shaft 162will return to the position as shown in FIG. 7A.

It should be understood that instead of a system that utilizes a pilotpressure control valve 114 to transmit the desired gauge wheel downforceFd to the direction control valve 140, any suitable electrical orelectro-mechanical device may be used to transmit the desired gaugewheel downforce Fd to the direction control valve 140. For example, asillustrated in FIGS. 8A-8C, a solenoid 400 may be employed to transmitthe desired gauge wheel downforce Fd against spool head 164. In such anembodiment, the control module 112 would send an electrical signal tothe solenoid 400 to cause the solenoid plunger 402 to be displacedcorresponding to the desired gauge wheel downforce Fd which in turn actsupon the spool head 164 causing the corresponding displacement of thespool 160 to open and close the ports as described and illustrated inconnection with FIGS. 7A-7B.

It should also be understood that the term “direction control valve” 140should not be construed as being limited to the embodiment described andillustrated herein, but should instead be understood to include anydevice or combination of devices that allows fluid flow to and/or fromthe downforce actuator 200 when the actual gauge wheel downforce Fabecomes imbalanced with the desired gauge wheel downforce Fd.

Because the gauge wheels 34 may occasionally encounter rocks or otherobstructions during planting operations that may cause high impactforces, the direction control valve 140 is preferably mounted in amanner to avoid damage from the impact forces. For example, thedirection control valve 140 is preferably bias mounted to allow thecontrol valve 140 to displace longitudinally if an abrupt force imposedby the lever 136 on the spool 160 causes the spool head 164 to bottomout against the head cap 170. When the abrupt force is removed, the biasmount returns the direction control valve 140 to its normal position.

In a preferred embodiment, the control module 112 cooperates with aGlobal Positioning System (GPS) and is configured to access a desireddownforce prescription map for setting and/or modifying the desiredgauge wheel downforce Fd as the planter traverses the field. Thedownforce prescription map may be based upon soil types, elevations, orlocation-specific preferences set by the operator prior to operation. Insuch an embodiment, the control module 112 may be used to specify adifferent desired gauge wheel downforce Fd to each row unit or groups ofrow units to more accurately follow the downforce prescription map. Forexample, if the locations of the far right row unit and the far left rowunit on the planter correspond to different prescribed desired gaugewheel downforces Fd based on soil type or other predefined factor, thecontrol module 12 is preferably capable of setting the appropriatedesired gauge wheel downforce Fd for each of the row units.

In addition, the control module 112 is preferably configured todetermine and display a ground contact percentage as disclosed inapplicant's co-pending international patent application no.PCT/US2008/050427 (Pub. No. W02009/042238), which is incorporated hereinin its entirety by reference. The control module 112 is preferablyconfigured to allow the operator to select a desired minimum groundcontact percentage in addition to, or rather than, inputting a specificdesired gauge wheel downforce Fd. In such an embodiment, the desiredgauge wheel downforce Fd would be the desired minimum ground contactpercentage. The dynamic system 100 would adjust the supplementaldownforce until the actual gauge wheel downforce Fa in relation to thedesired gauge wheel downforce Fd resulted in the desired minimum groundcontact percentage over the sampling period. Thus, as used herein, theterm “desired gauge wheel downforce Fd” should be understood to includea force that may be expressed as a numerical value or as a percentage ofground contact.

The closed-loop feedback circuit 110 preferably cooperates with atransport position detector 300 (FIG. 5), such as a height sensor orcontact switch disposed on the frame of the planter, to detect when theplanter is raised into a transport position. It should be appreciatedthat when the planter is raised, the gauge wheel arms 36 will pivotdownwardly resulting in the load sensor 116 to sense zero or near zeroactual gauge wheel downforce Fa, which in turn will result in fluid flowto the downforce actuator 200 until it is fully extended. To preventsuch a result from occurring, the transport position detector 300 ispreferably in electrical communication with a valve 310 disposed alongthe fluid supply line 122 c. When the detector 300 detects that theplanter is in a transport position, the valve 310 is closed to preventthe flow of fluid from the fluid source 130 to the fluid inlet ports 150of the direction control valves 140 of the row units 10. The valve 310is preferably a two-position normally open solenoid valve.

Alternatively, instead of a separate valve 310 disposed in the fluidsupply line 122 c, the transport position detector 300 may be inelectrical communication with the pilot pressure control valve 114 suchthat when the planter is raised into the transport position, thetransport position detector 300 sends a signal to cause the pilotpressure control valve 114 to close. In such an event the downforceactuators 200 will automatically “raise” in an effort to rebalance theload between Fd and Fa, by allowing fluid to flow through the directioncontrol valve 140 as indicated in FIG. 7C or 8C, because Fd will be zerowhen the pilot pressure control valve 114 is closed. When the loadsensor 116 senses zero when the gauge wheels are raised above the soilsuch that Fd=Fa, the direction control valve 140 will return to theposition illustrated in FIG. 7A or 8A preventing fluid flow to thedownforce actuator 200.

Furthermore, it should be understood that the pilot pressure controlvalve 114 and the control module 112 may be combined into a singlemanually operated pressure regulating valve. In such an embodiment, themanually operated pressure regulating valve would preferably includelabels or markers relating each pressure setting to the gauge wheelreaction force. In the same embodiment, the output pilot pressurescorresponding to the desired gauge wheel downforce Fd would also be setmanually. Such an embodiment is shown in FIG. 9, which illustrates aportion of the closed-loop feedback circuit 110 wherein control module112 and the pilot pressure valve 114 are replaced by a manually operatedpressure regulating valve 400. The valve 400 includes a controller 402such as a dial or knob, and settings 404 corresponding to the desiredgauge wheel downforce Fd, which may be indicated in pounds force asillustrated or in any other desired units.

In another embodiment, the load sensor 116 may include a piezoelectricload cell such as a compression load cell model no. FSH00402 availablefrom Futek in Irvine, Calif., which may be disposed between thedirection control valve 140 and the lever 136. Such an embodiment isillustrated in FIG. 10, in which a load cell 116 is mounted to thedistal end of the spool shaft 162 of the direction control valve 140.

The foregoing description is presented to enable one of ordinary skillin the art to make and use the invention and is provided in the contextof a patent application and its requirements. Various modifications tothe preferred embodiment of the apparatus, and the general principlesand features of the system and methods described herein will be readilyapparent to those of skill in the art. Thus, the present invention isnot to be limited to the embodiments of the apparatus, system andmethods described above and illustrated in the drawing figures, but isto be accorded the widest scope consistent with the spirit and scope ofthe appended claims.

1. A method of controlling supplemental downforce on a planter row unit,comprising: generating an actual gauge wheel downforce Fa on the planterrow unit; defining a desired gauge wheel downforce Fd; and modifyingsaid actual gauge wheel downforce Fa, wherein said step of modifyingsaid actual gauge wheel downforce Fa is accomplished using a first fluidcontrol apparatus, said fluid control apparatus being mounted to theplanter row unit.
 2. The method of claim 1, wherein said first fluidcontrol apparatus comprises a fluid control valve.
 3. The method ofclaim 1, wherein said first fluid control apparatus comprises a fluidmanifold, said fluid manifold having a plurality of fluid inputs and aplurality of fluid outputs.
 4. The method of claim 2, wherein said stepof modifying said actual gauge wheel downforce Fa is additionallyaccomplished using a second fluid control apparatus, said fluid controlapparatus being mounted to the planter row unit.
 5. The method of claim4, wherein said second fluid control apparatus comprises a fluidmanifold, said fluid manifold having a plurality of fluid inputs and aplurality of fluid outputs.
 6. The method of claim 1, further including:sending a command signal to a solenoid associated with said first fluidcontrol apparatus, wherein in response to receipt of said commandsignal, said solenoid causes said fluid control apparatus to modify anoperating state of said fluid control apparatus such that said actualgauge wheel downforce Fa becomes closer to said desired gauge wheeldownforce Fd.
 7. The method of claim 2, further including: sending acommand signal to a solenoid associated with said first fluid controlapparatus, wherein in response to receipt of said command signal, saidsolenoid causes said fluid control apparatus to modify an operatingstate of said fluid control apparatus such that said actual gauge wheeldownforce Fa becomes closer to said desired gauge wheel downforce Fd. 8.The method of claim 7, wherein said step of modifying said actual gaugewheel downforce Fa is additionally accomplished using a second fluidcontrol apparatus, said fluid control apparatus being mounted to theplanter row unit.
 9. The method of claim 8, wherein said second fluidcontrol apparatus comprises a fluid manifold, said fluid manifold havinga plurality of fluid inputs and a plurality of fluid outputs.
 10. Themethod of claim 2, further including: detecting that said planter rowunit is in a transport position; and upon detecting that said planterrow unit is in a transport position, modifying said desired gauge wheeldownforce Fd.
 11. The method of claim 2, wherein said row unit is one ofa plurality of row units each generating an actual gauge wheel downforceFa during planting operations and wherein said valve is one of aplurality of valves, each of which is associated with and mounted to oneof said plurality of row units, and wherein each of said plurality ofvalves is associated with one of a plurality of solenoids.
 12. Themethod of claim 2, further including: measuring said actual gauge wheeldownforce Fa using a load sensor mounted to said planter row unit. 13.The method of claim 11, wherein each of said plurality of valves adjustsa pressure in one of a plurality of downforce actuators in order tobring said actual gauge wheel downforce Fa closer to said desired gaugewheel downforce Fd at each row unit, each of said plurality of downforceactuators being disposed to modify said actual gauge wheel downforce Faon one of said plurality of row units.
 14. The method of claim 13,further including: sensing said actual gauge wheel downforce Fa on oneof said plurality of row units using a load sensor, said load sensordisposed to measure said actual gauge wheel downforce Fa, said loadsensor in electrical communication with a control module, said controlmodule defining said desired gauge wheel downforce Fd.
 15. The method ofclaim 14, further including: detecting that said planter row unit is ina transport position; and upon detecting that said planter row unit isin a transport position, modifying said desired gauge wheel downforce Fdfor all of said plurality of row units.